Learn in the textbookValidation, Acceptance, and Migration
DefinitionMigration (移行) is the work of switching data and operations from the current system to the new one until it is in live use.
ExplanationMigration includes software installation (ソフトウェア導入), which deploys and configures the software in the production environment, and the work of moving data from the old system and switching operations to the new one. The cutover method, such as running the old and new systems side by side for a set period, is chosen by weighing the risk of stopping operations against the effort involved. Fixes and changes to programs after live operation begins are called software maintenance (ソフトウェア保守).
AnalogyIt is like moving a shop into a new building: you fix the opening day and who is in charge, install the shelves and equipment, bring in the stock, and then put up the new sign.
Memory hookIn English it is migration, the same word used for birds that change homes with the seasons, so picture moving house with all your belongings.